It's a big year 2012, a year fat with events. This summer there's the Olympics (double PE with an inflated sense of self-worth and even more rules about plimsolls), there's the end of the world itself in mid-December (argh!), and before that, on 29 February, there's Leap Day, the one day every four years when women are encouraged to propose to their boyfriends.

One day every four years. One day out of 1,460 [see footnote]. That's around 0.068% of the time, compared with, like, 100 minus 0.068% of the time, when it's thought to be completely inappropriate and really quite gauche. That's weird, isn't it? Seriously – isn't it? I do have to ask, because I know sometimes I get things wrong. Sometimes I think things are weird and then they turn out to be completely unweird, like keeping condiments in the fridge, or belief in God, so I do need to be told. It feels like bad maths, more than anything. It feels like the marriage equivalent of Take Our Daughters to Work Day, a day of mild hysteria and awkward chat about GCSE options. A day that occurs so infrequently it seems to revel in its oddness, its wrongness – it's the antique stamp with a missing perforation, a thing whose abnormality adds value.

And it happens on 29 February. Because this is a day that shouldn't really exist. It's a blip on the calendar. It's out of time. It's the midnight of the year – a no-man's land, a gauzy curtain between night and day, a time when ghosts appear. Leap Day is the day when weird things are allowed to happen, when the usual structures can melt just slightly, when spoons bend and women are given this inch of power, this moment they can ask for what they want.

The American tradition, Sadie Hawkins Day, is based on a 1930s comic-strip character who was so ugly no man would ever propose to her. Some historians believe the British tradition (dating from the 19th century) spans the whole leap year. Others say it was tightened to just one day as men felt too vulnerable: if women were planning to propose, they were expected to wear red petticoats as a warning – the opposite of a red rag to a bull; a sign for the man to run away. Online, postcards from leap year 1908 show women catching men with butterfly nets, and old maids with many chins setting silver bear traps.

But it's not that women actually do propose on the 29th – it's that the day highlights the fact that the rest of the time it's the man's decision. In the "tradition that legitimises the subjugation of women" charts, it's right up there with the taking of the husband's name, isn't it. As a day of pseudo-strength, when the woman is gifted a few hours of power, it serves only to underline her powerlessness the rest of the year, the rest of the four years.

Why do we perpetuate this bizarreness? Why today, when it's widely realised (in my extended world at least) that men are no more afraid of commitment than women, why might they feel emasculated by a proposal in 2011 but not 2012? And what would happen if women were encouraged to propose marriage whenever they were ready for it? Would more relationships shatter? Would the high street be a parade of weddings? Would Britain turn into a 3D-version of Bridezillas, one long, long hen night, the sky dark, sunlight obscured by penis-shaped deely boppers, a wave of black sambuca slowly washing all rubble, all mini-sausage rolls away to sea?

Or would it be, sort of, OK? Would it help make us all less freako about relationships? Would it help make women less anxious, less driven by "rules", and men more likely to phone them the day after simple sex? I do have to ask, because sometimes I get things wrong.

• This correction was published on 15 January 2012:A piece on leap years lamented that 29 February was "the one day every four years when women are encouraged to propose to their boyfriends… one day out of 1,460." But as one of those years is a leap year, it's one day out of 1,461 – an even greater injustice (Up Front, Observer Magazine).